JP4849107B2 - Integrated circuit device and electronic apparatus - Google Patents

Integrated circuit device and electronic apparatus Download PDF

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JP4849107B2
JP4849107B2 JP2008226368A JP2008226368A JP4849107B2 JP 4849107 B2 JP4849107 B2 JP 4849107B2 JP 2008226368 A JP2008226368 A JP 2008226368A JP 2008226368 A JP2008226368 A JP 2008226368A JP 4849107 B2 JP4849107 B2 JP 4849107B2
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data
correction
correction data
calculation
voltage
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JP2010060842A (en
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晶 森田
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セイコーエプソン株式会社
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    • GPHYSICS
    • G09EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09GARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/34Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
    • G09G3/36Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source using liquid crystals
    • G09G3/3611Control of matrices with row and column drivers
    • G09G3/3648Control of matrices with row and column drivers using an active matrix
    • GPHYSICS
    • G09EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09GARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/2007Display of intermediate tones
    • G09G3/2011Display of intermediate tones by amplitude modulation
    • GPHYSICS
    • G09EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09GARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/34Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
    • G09G3/36Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source using liquid crystals
    • G09G3/3611Control of matrices with row and column drivers
    • G09G3/3685Details of drivers for data electrodes
    • G09G3/3688Details of drivers for data electrodes suitable for active matrices only
    • GPHYSICS
    • G09EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09GARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2310/00Command of the display device
    • G09G2310/02Addressing, scanning or driving the display screen or processing steps related thereto
    • G09G2310/0264Details of driving circuits
    • G09G2310/0297Special arrangements with multiplexing or demultiplexing of display data in the drivers for data electrodes, in a pre-processing circuitry delivering display data to said drivers or in the matrix panel, e.g. multiplexing plural data signals to one D/A converter or demultiplexing the D/A converter output to multiple columns
    • GPHYSICS
    • G09EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09GARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2320/00Control of display operating conditions
    • G09G2320/02Improving the quality of display appearance
    • G09G2320/0204Compensation of DC component across the pixels in flat panels
    • GPHYSICS
    • G09EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09GARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2320/00Control of display operating conditions
    • G09G2320/02Improving the quality of display appearance
    • G09G2320/029Improving the quality of display appearance by monitoring one or more pixels in the display panel, e.g. by monitoring a fixed reference pixel
    • G09G2320/0295Improving the quality of display appearance by monitoring one or more pixels in the display panel, e.g. by monitoring a fixed reference pixel by monitoring each display pixel

Description

  The present invention relates to an integrated circuit device, an electronic device, and the like.

  In recent years, high-definition video technology such as high-definition video has become widespread, and along with this, display devices (electronic devices) such as liquid crystal projectors have become higher definition and multi-gradation. In such a multi-gradation display device, a highly accurate analog circuit is required for a driver for driving a liquid crystal panel (electro-optical panel).

  Specifically, since the gradation voltage per gradation decreases as the number of gradations increases, the gradation is not correctly expressed only by a slight error in the driving voltage of the driver. For example, when there is an offset difference between operational amplifiers that drive adjacent data voltage supply lines (data lines, source lines), a difference occurs in the voltage of adjacent data voltage supply lines, resulting in a vertical line on the display image. appear. As described above, a driver used in a multi-gradation display device has a problem of outputting a data voltage with high accuracy.

  For example, Patent Document 1 discloses a technique for improving the accuracy of data voltage by driving a data voltage supply line with an operational amplifier and then driving with a DAC output. According to this method, it is possible to prevent an error in the data voltage due to the offset of the operational amplifier by driving the data voltage supply line with the DAC output.

  However, the higher the definition of the liquid crystal panel, the faster the data voltage supply line needs to be driven. In the method of Patent Document 1, since a DAC output having a higher output impedance than that of an operational amplifier is used, there is a problem that it takes time until the data voltage reaches a desired gradation voltage.

  On the other hand, Patent Document 2 discloses a technique for correcting display unevenness of a liquid crystal projector by performing interpolation calculation on correction data stored in a RAM and adding it to video data. According to this method, by correcting video data by digital processing, it is possible to output a data voltage with high accuracy and to drive at high speed by an operational amplifier with high driving power.

However, the characteristics of the liquid crystal panel and driver deteriorate with time after shipment. Further, the characteristics change due to heat generated by a display device such as a projector lamp. In the method of Patent Document 2, since correction is performed using correction data adjusted at the time of manufacturing a liquid crystal panel or the like, there is a problem that it is not possible to cope with such a change in characteristics after shipment.
Japanese Patent No. 3405333 JP 2002-108298 A

  According to some embodiments of the present invention, it is possible to provide an integrated circuit device and an electronic apparatus that can correct variation in data voltage in real time.

  According to one embodiment of the present invention, a plurality of data line driving circuits for driving a plurality of data voltage supply lines and a data voltage corresponding to a correction target data line driving circuit among the plurality of data line driving circuits are compared with a comparator reference A comparator for comparing with voltage, a correction data calculating unit for calculating correction data for correcting variation in the data voltage based on a comparison result from the comparator, and image data based on the correction data from the correction data calculating unit And a plurality of correction circuits for outputting the corrected image data to the corresponding data line driving circuit among the plurality of data line driving circuits.

  According to one aspect of the present invention, the comparator compares the data voltage output from the data line driving circuit to be corrected with the comparator reference voltage and outputs a comparison result, and the correction data calculation unit corrects the correction data based on the comparison result. The correction circuit corrects the image data based on the correction data, outputs the corrected image data to the corresponding data line driving circuit, and the data line driving circuit drives the corresponding data voltage supply line.

  Thus, according to one embodiment of the present invention, variation in data voltage output from the data line driver circuit can be corrected. Therefore, even when there is a manufacturing variation in the data line driving circuit, the data voltage corresponding to the image data can be output with high accuracy. As a result, even with pixels driven by different data line driving circuits, image data of the same gradation can be displayed with exactly the same luminance, so that the image quality can be improved.

  In one aspect of the present invention, in the correction data calculation mode, the correction data calculation unit sequentially changes the measurement data and outputs the measurement data to the correction target data line driving circuit. A data voltage corresponding to the measurement data is output, the comparator compares the data voltage corresponding to the measurement data with a comparator reference voltage, and the correction data calculation unit is based on the comparison result from the comparator. In the normal operation mode, the correction circuit corrects the image data based on the correction data, and outputs the corrected image data to the corresponding data line driving circuit among the plurality of data line driving circuits. May be.

  According to one aspect of the present invention, the correction data calculation unit calculates correction data in the correction data calculation mode, and the correction circuit corrects image data based on the correction data in the normal operation mode. Therefore, the variation in the data voltage output from the data line driving circuit can be corrected in real time. As a result, even when the output characteristics of the data line driving circuit change due to external factors such as heat, it is possible to prevent the image quality from deteriorating.

  In the aspect of the invention, the correction data calculation unit may calculate the correction data by executing the correction data calculation mode in one horizontal scanning period in the non-display period of the vertical scanning period.

  As described above, by calculating the correction data for each vertical scanning period, it is possible to correct the variation in the data voltage in real time. Further, by calculating the correction data in the non-display period, it is possible to correct the data voltage variation without affecting the image display.

  In one aspect of the present invention, the correction data calculation unit sequentially outputs first to kth (k is a natural number) measurement gradation data as the measurement data, and the comparator is configured to perform the first measurement. Comparing the comparator reference voltage, which is the voltage between the gradation voltage corresponding to the gradation data and the gradation voltage corresponding to the nth measurement gradation data, with the data voltage corresponding to the data line driving circuit to be corrected May be.

  According to one aspect of the present invention, the correction data calculation unit sequentially outputs the first to kth measurement gradation data. Accordingly, the correction data calculation unit can output the measurement data by sequentially changing the measurement data within a predetermined range. According to one embodiment of the present invention, the comparator uses the voltage between the grayscale voltage corresponding to the first measurement grayscale data and the grayscale voltage corresponding to the kth measurement grayscale data as the comparator reference voltage. Use. Thereby, the comparator reference voltage is appropriately set.

  In one embodiment of the present invention, in the first horizontal scanning period among the plurality of horizontal scanning periods in the non-display period, the plurality of data voltage supply lines are set to a predetermined data voltage, and the plurality of data voltage supply lines in the non-display period are set. In the second horizontal scanning period following the first horizontal scanning period in the horizontal scanning period, the correction data calculation unit may obtain the correction data.

  According to one aspect of the present invention, the plurality of data voltage supply lines are set to a constant voltage in one horizontal scanning period before the correction data calculation. As a result, the correction data can be calculated starting from the same data voltage every time correction data calculation is started, and correction data that accurately reflects variations in the data voltage can be obtained.

  In one aspect of the present invention, the correction data calculation unit multiplies the correction data obtained from the comparison result of the comparator and the correction coefficient in the correction data calculation mode to obtain correction data after coefficient multiplication, The plurality of correction circuits may correct the image data based on the correction data after coefficient multiplication in the normal operation mode.

  As a result, the variation in data voltage can be corrected accurately using the correction data after coefficient multiplication. For example, even when the driving capability of the data line driving circuit is insufficient in the correction data calculation mode, the correction data that has not been accurately calculated due to the insufficient driving capability can be corrected with the correction coefficient.

  In the aspect of the invention, the correction data calculation unit may be configured such that, in the correction data calculation mode, when the measurement data is sequentially changed within a predetermined range, the comparison result of the comparator is the first level or If it is fixed at one of the second levels, it may be determined that the overflow has occurred, and overflow data may be output as correction data for the data line drive circuit to be corrected.

  According to one aspect of the present invention, overflow data is output as correction data when the variation in data voltage exceeds the measurement range. Thereby, correction data can be output even in the case of overflow.

  In the aspect of the invention, the correction data calculation unit may output a predetermined constant as the overflow data.

  In this way, overflow data can be realized by using a predetermined constant, and correction data can be output even in the case of overflow.

  In one embodiment of the present invention, each data line driving circuit of the plurality of data line driving circuits performs multiplex driving in which data voltages are written to a plurality of pixels in one horizontal scanning period, and the correction data calculation unit In one horizontal scanning period in the non-display period of the scanning period, a plurality of correction calculation data for the correction target data line driving circuit may be obtained, and the correction data may be obtained based on the plurality of correction calculation data. .

  According to one aspect of the present invention, a plurality of correction calculation data is obtained in one horizontal scanning period, and correction data is obtained using the plurality of correction calculation data. Thereby, accurate correction data can be obtained. For example, even when inaccurate correction calculation data is calculated due to the influence of noise or the like, accurate correction data can be obtained by using a plurality of correction calculation data.

  In the aspect of the invention, the correction data calculation unit may obtain the correction data by averaging the plurality of correction calculation data.

  Accordingly, correction data can be calculated from a plurality of correction calculation data. Further, it is possible to obtain accurate correction data by averaging the influence of noise and the like by averaging processing.

  In the aspect of the invention, the correction data calculation unit may be configured such that, in the correction data calculation mode, when the measurement data is sequentially changed within a predetermined range, the comparison result of the comparator is the first level or If it is fixed at either one of the second levels, it may be determined that an overflow has occurred, and overflow data may be used as correction measurement data for the data line drive circuit to be corrected.

  According to one aspect of the present invention, when an overflow occurs in the calculation of the correction calculation data, the overflow data is used as the correction calculation data. Thereby, even when some of the correction calculation data calculated in one horizontal scanning period overflow, the correction data can be calculated using the overflow data.

  In one aspect of the present invention, the correction data calculation unit is for correction calculation of the sth (1 ≦ s ≦ t, where s and t are integers of 2 or more) of the first to tth correction calculation data. If it is determined that the overflow occurs when obtaining data, the first to s-1th correction calculation data among the first to tth correction calculation data is averaged to obtain overflow data; The data may be used as the s-th correction calculation data.

  Thereby, when overflow occurs in the calculation of the correction calculation data, it is possible to obtain the overflow data close to the actual data voltage variation. As a result, the variation in data voltage can be accurately corrected.

  In one aspect of the present invention, the correction data calculation unit uses the current correction data and the previous correction data obtained for the data line driving circuit to be corrected, and uses the correction data of the plurality of correction circuits. Correction data to be output to a correction circuit corresponding to the data line driving circuit may be obtained.

  As a result, variations in data voltage can be corrected correctly, and deterioration of image quality can be prevented. For example, even when inaccurate correction data is calculated due to the influence of noise or the like, the current correction data can be corrected using the previous correction data.

  In one aspect of the present invention, when the current correction data is larger than the previous correction data, the correction data calculation unit adds the predetermined positive value to the previous correction data to obtain the correction data. In addition, when the current correction data is smaller than the previous correction data, the correction data is obtained by adding a negative predetermined value to the previous correction data.

  According to one aspect of the present invention, the variation amount of the correction data is limited to a positive or negative predetermined value using the correction data calculated last time. Therefore, the correction data can be changed gradually when correction data having a value significantly different from the previous correction data is calculated. As a result, image quality deterioration such as display unevenness due to a sudden change in correction data can be prevented.

  In one embodiment of the present invention, the correction data calculation unit sets a timing to start monitoring the comparison result of the comparator, and a measurement period register sets a period to monitor the comparison result of the comparator And may be included.

  Accordingly, the timing at which the correction data calculation unit starts monitoring the comparison result and the period during which the correction data calculation unit monitors the comparison result can be adjusted.

  In one embodiment of the present invention, when the plurality of data line driving circuits are arranged along a first direction, and the direction opposite to the first direction is the second direction, the comparator includes: The plurality of data line driving circuits may be arranged in the first direction or the second direction.

  As a result, the data line driving circuits can be arranged at equal intervals. Therefore, the process processing accuracy of the data line driving circuit can be made uniform, and variations in data voltage due to manufacturing variations can be suppressed. In addition, it is possible to more accurately correct the variation in the data voltage using the correction data.

  Another embodiment of the present invention relates to an electronic device including the integrated circuit device described above.

  Hereinafter, preferred embodiments of the present invention will be described in detail. The present embodiment described below does not unduly limit the contents of the present invention described in the claims, and all the configurations described in the present embodiment are indispensable as means for solving the present invention. Not necessarily.

1. Data voltage correction circuit 1.1. Configuration Example Hereinafter, as an application example of the present embodiment, a case where a liquid crystal panel (electro-optical panel in a broad sense) is driven according to the present embodiment will be described. As the liquid crystal panel, for example, an active matrix type panel using a switching element such as a TFT (Thin Film Transistor) or a TFD (Thin Film Diode) or a simple matrix type panel can be used. However, the present invention can also be applied when driving an electro-optical panel other than the liquid crystal panel. For example, the present invention can also be applied to driving a display panel using a self-luminous element such as an organic EL (Electro Luminescence) element or an inorganic EL element.

  FIG. 1 shows a configuration example of this embodiment. The configuration example of this embodiment includes first to nth data line driving circuits 140-1 to 140-n (a plurality of data line driving circuits), first to nth correction circuits 160-1 to 160-n ( A plurality of correction circuits), a comparator 180, a control unit 100, and a selection circuit 120. The control unit 100 includes a correction data calculation unit 102. Various modifications may be made such as omitting some of these components, adding other components, and changing the connection relationship.

  In the present embodiment, variations (deviations and errors) of the first to nth data voltages SV1 to SVn (a plurality of data voltages) are corrected in the correction data calculation mode and the normal operation mode. Specifically, in the correction data calculation mode, the correction data calculation unit 102 measures variations in the data voltages SV1 to SVn to obtain correction data CD1 to CDn. In the normal operation mode, the correction circuits 160-1 to 160-n correct the image data PD1 to PDn using the correction data CD1 to CDn, and the data line drive circuits 140-1 to 140-n correct the image data after the correction processing. In response to PCD1 to PCDn, data voltages SV1 to SVn are output. Accordingly, the present embodiment can drive an electro-optical panel such as a liquid crystal panel in a state where output variations of the data line driving circuits 140-1 to 140-n are corrected.

  For example, variations in the data voltages SV1 to SVn occur due to offsets in operational amplifiers OP1 to OPn described later in FIG. 8 and variations in output characteristics of the D / A conversion circuits DAC1 to DACn. At this time, even if the same gradation data is input to the data line driving circuits 140-1 to 140-n, the data voltages SV1 to SVn are not uniform due to an offset or the like. In the present embodiment, the correction data CD1 to CDn are used to cancel these offsets, and the data voltages SV1 to SVn corresponding to the same gradation data are made uniform, thereby correcting variations in the data voltages SV1 to SVn.

  Specifically, the correction data calculation unit 102 receives the comparison result CPQ from the comparator 180 and obtains correction data corresponding to the correction target data line driving circuit (hereinafter, correction target correction data). For example, a part of the correction data CD1 to CDn as correction data to be calculated is obtained in one correction data calculation, and this correction data calculation is repeated to obtain correction data CD1 to CDn.

  More specifically, in the correction data calculation mode, the correction data calculation unit 102 sequentially changes the measurement data MD within a predetermined range and outputs the measurement data MD to the correction circuits 160-1 to 160-n. Data line driving circuits 140-1 to 140-n output data voltages corresponding to measurement data MD as data voltages SV1 to SVn. Then, the comparator 180 compares the data voltage output from the correction target data line driving circuit (hereinafter referred to as the correction target data voltage) with the comparator reference voltage VP and outputs a comparison result CPQ. Based on the result CPQ, correction data to be calculated is obtained.

  For example, the correction data calculation unit 102 sequentially outputs the measurement gradation data MGD1 to MGDk (k is a natural number) one by one as the measurement data MD, and the correction target data line driving circuit outputs the measurement gradation data MGD1 to MGD1. Data voltages corresponding to MGDk are sequentially output. Then, the comparator 180 outputs a comparison result CPQ corresponding to each of the measurement gradation data MGD1 to MGDk. The correction data calculation unit 102 detects an edge (change point) of the comparison result CPQ as will be described later with reference to FIG. 2 and the like, and obtains correction data to be calculated using the measurement gradation data when the edge is detected. .

  The correction circuits 160-1 to 160-n receive the measurement data MD, the correction data CD1 to CDn, and the image data PD1 to PDn, and send the measurement data MD or the corresponding data line drive circuits 140-1 to 140-n. The corrected image data PCD1 to PCDn are output. Specifically, in the correction data calculation mode, the correction circuits 160-1 to 160-n output the measurement data MD. In the normal operation mode, the correction circuits 160-1 to 160-n correct the image data PD1 to PDn with the correction data CD1 to CDn and output the image data PCD1 to PCDn. For example, AD1 to ADn described later in FIG. 8 perform correction processing by adding image data PD1 to PDn and correction data CD1 to CDn.

  The data line drive circuits 140-1 to 140-n receive the measurement data MD or the image data PCD1 to PCDn from the correction circuits 160-1 to 160-n and receive the first to nth data voltage supply lines S1 to S1. Sn (a plurality of data voltage supply lines) is driven. Specifically, in the correction data calculation mode, the data line driving circuits 140-1 to 140-n output data voltages SV1 to SVn corresponding to the measurement data MD. In the normal operation mode, the data line driving circuits 140-1 to 140-n output data voltages SV1 to SVn corresponding to the corrected image data PCD1 to PCDn.

  The selection circuit 120 selects a data voltage to be corrected from the data voltages SV1 to SVn and outputs it as the input voltage CPI of the comparator 180. For example, the selection circuit 120 receives the selection signal SL from the control unit 100 and selects a data voltage as shown in FIG.

  Comparator 180 receives input voltage CPI (data voltage to be corrected) and comparator reference voltage VP, and outputs comparison result CPQ. Specifically, based on the magnitude relationship between the data voltage to be corrected and the comparator reference voltage VP, the H level (first logic level) or the L level (second logic level) is output as the comparison result CPQ. 2, the comparator reference voltage VP is a voltage within the range of the data voltage corresponding to the measurement data MD when the correction data calculation unit 102 changes the measurement data MD within a predetermined range. is there. For example, the comparator reference voltage VP may be supplied from the power supply circuit 50 shown in FIG. 3, or may be a voltage obtained by dividing the voltage supplied from the power supply circuit 50 with a resistor.

  The control unit 100 controls the operation of the components of this embodiment, and controls the operation timing in the correction data calculation mode and the normal operation mode. For example, the control unit 100 outputs a selection signal SL to the selection circuit 120, and outputs a correction enable signal C_Enable to the correction circuits 160-1 to 160-n. Further, as will be described later with reference to FIG. 9, the calculation timing of the correction data CD1 to CDn is controlled using the sequencer 240, the counter unit 200, and the like.

1.2. Explanation of Operation of Correction Data Calculation The operation in the correction data calculation mode will be described in detail with reference to FIGS. 2A and 2B. FIG. 2A schematically shows a waveform example of the data voltage to be corrected in the correction data calculation unit mode. FIG. 2B schematically shows a waveform example of the comparison result CPQ of the comparator 180 in the correction data calculation unit mode.

  In FIGS. 2A and 2B, the correction data calculation unit 102 obtains correction data CDi (1 ≦ i ≦ n, i is a natural number) as correction data to be calculated, and 8 as measurement data MD. An example of outputting the measurement grayscale data MGD1 to MGD8 (k = 8) will be described. However, the same applies when obtaining other correction data other than the correction data CDi. Further, the correction data calculation unit 102 may obtain a plurality of correction data as the correction data to be calculated, and may output the number of measurement gradation data other than eight as the measurement data MD.

  In the correction data calculation mode, the correction data calculation unit 102 outputs measurement gradation data MGD1 to MGD8. The correction circuit 160-i outputs the measurement gradation data MGD1 to MGD8 from the correction data calculation unit 102 to the data line driving circuit 140-i. Then, as indicated by LC1 in FIG. 2A, the data line driving circuit 140-i changes the data voltage indicated by C2 from the data voltage indicated by C1 as the measurement gradation data MGD1 to MGD8 sequentially change. The voltage SVi is sequentially output. The selection circuit 120 selects the data voltage SVi and outputs it to the comparator 180 as the comparator input voltage CPI, and the comparator 180 outputs the comparison result CPQ.

  For example, the data voltage SVi corresponding to the measurement gradation data MGD2 is smaller than the comparator reference voltage VP as indicated by C3 in FIG. 2A, and the data voltage SVi corresponding to the measurement gradation data MGD3 as indicated by C4. Is greater than the comparator reference voltage VP. In this case, the comparison result CPQ indicated by LC3 in FIG. 2B corresponds to the L level corresponding to the measurement gradation data MGD2 as indicated by C5, and corresponds to the measurement gradation data MGD3 as indicated by C6. Becomes H level. Then, the correction data calculation unit 102 detects the edge that changes from the L level to the H level, and sets MGD3 that is the measurement gradation data when the edge is detected as the correction data CDi.

  In this manner, the present embodiment can obtain correction data for correcting a data voltage variation.

  Here, it is assumed that the data voltage SVi does not vary due to an offset or the like. At this time, as indicated by LC2 in FIG. 2A, the data voltage SVi sequentially changes from the data voltage indicated by C7 to the data voltage indicated by C8. This data voltage SVi is an ideal data voltage corresponding to the measurement gradation data MGD1 to MGD8. As described with reference to FIG. 1, the comparator 180 uses a voltage between the ideal minimum value (C7) and maximum value (C8) of the data voltage as the comparator reference voltage VP. For example, a data voltage corresponding to the measurement gradation data MGD5 is used as indicated by C9. Then, when it is assumed that there is no variation due to offset or the like, the comparison result CPQ changes as indicated by LC4 in FIG. 2B, and the correction data CDi becomes the measurement gradation data MGD5.

  As indicated by LC1 in FIG. 2A, the data voltage SVi actually output from the data line driver circuit 140-i in the correction data calculation mode is the ideal data voltage SVi indicated by LC2 in FIG. On the other hand, variation VOFi (offset) is included. According to the correction data calculation method, the actually measured correction data CDi = MGD3 and the correction data CDi = MGD5 for the ideal data voltage are different correction data by the number of gradations corresponding to the variation VOFi. Therefore, in this embodiment, the variation VOFi of the data voltage SVi can be corrected by correcting the image data PDi using the correction data CDi = MGD3.

  By the way, if the data voltage varies, the display quality deteriorates because the luminance is different for each data voltage supply line even though the same gradation is output. Therefore, there has been a problem that a data voltage is output with high accuracy in a driver for driving a liquid crystal panel.

  In this regard, according to the present embodiment, the correction data calculation unit 102 outputs the measurement data MD in the correction data calculation mode, and the data line driving circuits 140-1 to 140-n correspond to the data voltage corresponding to the measurement data MD. SV1 to SVn are output, the comparator 180 compares the data voltages SV1 to SVn with the comparator reference voltage VP and outputs the comparison result CPQ, and the correction data calculation unit 102 calculates the correction data CD1 to CDn from the comparison result CPQ. In the normal operation mode, the image data PD1 to PDn are corrected using the correction data CD1 to CDn.

  As a result, variations in the data voltages SV1 to SVn can be corrected, and data voltages corresponding to the image data PD1 to PDn can be output with high accuracy. Therefore, even on pixels (subpixels or dots in a narrow sense) on different data voltage supply lines, the same gradation data can be displayed with the same luminance, and the image quality can be improved. For example, a driver for a high-definition liquid crystal panel generally has a large number of gradations and a small gradation voltage per gradation, so that the image quality is likely to deteriorate due to variations in data voltage. Specifically, luminance unevenness such as vertical lines occurs in the display image. In the present embodiment, variations in the data voltages SV1 to SVn can be corrected, so that deterioration of image quality can be prevented even when a high-definition liquid crystal panel is driven.

  For example, as another method of correcting the data voltage variation, the data voltage supply line is directly driven by the DAC output that converts the grayscale data into the grayscale voltage, thereby preventing the data voltage variation due to the offset of the operational amplifier. There was a technique to do. However, since the output impedance of the DAC is higher than that of the operational amplifier, there is a problem that driving time is insufficient in driving a high-definition liquid crystal panel or in multiplex driving that outputs a plurality of data voltages in one horizontal period.

  In this regard, in the present embodiment, the variations in the data voltages SV1 to SVn are corrected by correcting the image data PD1 to PDn using the correction data CD1 to CDn. Therefore, output variations of the data line driving circuits 140-1 to 140-n can be corrected on the data. Thereby, as will be described later with reference to FIG. 8, for example, the data voltage supply lines S1 to Sn can be driven at high speed using the operational amplifiers OP1 to OPn.

  For example, as another method of correcting the variation in data voltage, there is a method of measuring the variation in data voltage at the time of shipment and storing the correction data, and correcting the variation in the data voltage using the correction data. . However, this method has a problem that it cannot cope with characteristic changes after shipment.

  In this regard, according to the present embodiment, the comparator 180 compares the data voltages SV1 to SVn with the comparator reference voltage VP, and the correction data calculation unit 102 receives the comparison result CPQ and calculates the correction data CD1 to CDn. As a result, variations in the data voltages SV1 to SVn can be measured and corrected in real time. Therefore, it is possible to prevent the image quality from being deteriorated even when the characteristics of the driver are changed after shipment or when the characteristics of the driver are changed by heat of the backlight or the like.

  For example, as will be described later with reference to FIG. 9 and the like, in this embodiment, the correction data CD1 to CDn may be calculated in the 1H mode in which the correction data is calculated in the non-display period of the frame (vertical scanning period). For example, correction data CD1 to CDn may be calculated in n frames by calculating one correction data as correction data to be calculated for each frame.

  As described above, by calculating the correction data CD1 to CDn for each frame, it is possible to correct variations in the data voltages SV1 to SVn in real time while displaying an image. Therefore, it is possible to cope with a change in characteristics over time after shipment of the driver. Further, by calculating the correction data CD1 to CDn in the non-display period, it is possible to correct the variations in the data voltages SV1 to SVn without affecting the image display.

  Here, as will be described later with reference to FIG. 3 and the like, in this embodiment, multiplex driving may be performed. In multiplex driving, each of the data line driving circuits 140-1 to 140-n drives a plurality of data lines (for example, data lines S1i to S8i in FIG. 3) on the liquid crystal panel in one horizontal scanning period. At this time, the correction data calculation unit 102 may obtain a plurality of correction calculation data in one horizontal scanning period. Specifically, the correction calculation data is calculated by a method similar to the calculation method described in FIG. Then, correction data may be calculated from the plurality of correction calculation data.

  By the way, when the variation in the data voltage cannot be measured accurately due to the influence of noise or the like, there is a problem that it is not possible to obtain correction data that accurately reflects the variation in the data voltage.

  In this respect, in the present embodiment, a plurality of correction calculation data is obtained in one horizontal scanning period, and correction data is obtained using the plurality of correction calculation data. Thus, even when some correction calculation data becomes inaccurate due to the influence of noise or the like, accurate correction data can be obtained by using a plurality of correction calculation data.

  For example, the correction data calculation unit 102 may calculate correction data by averaging a plurality of correction calculation data. Specifically, the correction data calculation unit 102 may perform addition averaging as the averaging process, or may weight each correction calculation data and average it. Further, the correction data calculation unit 102 may add or subtract a constant in the averaging process.

  Accordingly, correction data can be calculated from a plurality of correction calculation data, and the influence of noise or the like can be prevented.

  For example, gradation data GD + ΔGD1 to GD + ΔGDk may be output as measurement gradation data MGD1 to MGDk to obtain a plurality of correction calculation data. Then, the correction data may be obtained by subtracting the gradation data GD from the average of the plurality of correction calculation data.

  Thereby, the variation in the data voltage can be measured in the data voltage corresponding to the gradation data GD. Then, by subtracting the gradation data GD from the average of the plurality of correction calculation data, it is possible to extract correction data corresponding to the data voltage variation.

  Here, in the case of multiplex driving in which p data lines (p is an integer of 2 or more) are driven by one data line driving circuit as the plurality of data lines, the correction data calculation unit 102 sets the plurality of data as correction calculation data. p correction calculation data may be obtained.

  In this case, each of the data line driving circuits 140-1 to 140-n has a capability of driving p data lines in one horizontal scanning period in the normal operation mode. Therefore, in the correction data calculation mode, p data lines can be driven in the same horizontal scanning period to measure p correction calculation data. In addition, the accuracy of the data voltage depends on the drive time, but by making the drive time per data line equal in the normal operation mode and the correction data calculation mode, the data voltage accuracy is equivalent to that in the normal operation mode. Correction data CD1 to CDn can be obtained. As a result, the data voltages SV1 to SVn can be accurately corrected.

  However, in multiplex driving, a plurality of correction calculation data is obtained in one horizontal period, and a plurality of measurement gradation data are used when obtaining one correction calculation data. For this reason, when the operational capability of the operational amplifier is insufficient, there is a problem that the data voltage corresponding to each measurement gradation data is not sufficiently driven and the variation in the data voltage cannot be measured accurately.

  According to the present embodiment, as will be described later with reference to FIG. 7, correction data CD1 to CDn are multiplied by the correction coefficient in the correction data calculation mode to obtain correction data after coefficient multiplication, and correction data after coefficient multiplication is performed in the normal operation mode. The image data PD1 to PDn may be corrected based on the above.

  As described above, in the present embodiment, correction data that has not been accurately calculated due to a lack of operational capability of the operational amplifier is corrected using the correction coefficient. As a result, variations in the data voltages SV1 to SVn can be accurately corrected.

  Here, in the present embodiment, when the correction data calculation unit 102 sequentially changes the measurement data MD within a predetermined range, the comparison result CPQ is L level (first level) or H level (second level). ) May be determined as overflow, and the overflow data may be used as the correction calculation data.

  Specifically, the correction data calculation unit 102 may use a predetermined constant as the overflow data. For example, gradation data between the maximum gradation data and the minimum gradation data of the measurement gradation data MGD1 to MGDk output from the correction data calculation unit 102 may be used as the predetermined constant.

  As described above, in this embodiment, when it is determined that the variation in the data voltage exceeds the measurement range, the correction data is obtained using the overflow data. Thereby, even when the calculation of the correction calculation data overflows due to the influence of noise or the like, the correction data reflecting the variation in the data voltage can be obtained as accurately as possible.

  The correction data calculation unit 102 overflows when obtaining the s-th correction calculation data (1 ≦ s ≦ t, where s and t are integers of 2 or more) among the first to t-th correction calculation data. The first to s-1th correction calculation data among the first to tth correction calculation data is averaged to obtain overflow data to obtain the sth correction calculation data. It may be used as

  As described above, in this embodiment, the correction calculation data for the times determined to be overflow are obtained from the correction calculation data obtained before the overflow is determined. As a result, it is possible to eliminate the influence of overflow due to noise or the like, obtain correction data reflecting more actual data voltage variation, and correct the data voltage variation accurately.

  However, when it is continuously affected by noise or the like, inaccurate correction data may be calculated even when the overflow process is performed. For example, when calculating correction data repeatedly in 1H mode or the like, if inaccurate correction data is suddenly calculated for a data line for which correction data has been calculated accurately, the luminance of the pixels on the data line is increased. It changes suddenly and the vertical line blinks on the displayed image.

  In this regard, according to the present embodiment, the correction data calculation unit 102 uses the current correction data obtained for the correction target data line driving circuit and the previous correction data to perform correction corresponding to the correction target data line driving circuit. You may ask for data.

  For example, when the current correction data is larger than the previous correction data, the correction data may be obtained by adding a positive predetermined value to the previous correction data. When the correction data obtained this time is smaller than the previous correction data, the correction data may be obtained by adding a negative predetermined value to the previous correction data.

  As described above, in the present embodiment, in the correction data repeatedly calculated in the 1H mode or the like, the variation amount restriction is performed to limit the variation amount of the correction data within a predetermined value using the previously calculated correction data. Thereby, even when inaccurate correction data is suddenly calculated due to the influence of noise or the like, it is possible to prevent vertical lines from being displayed on the display image.

  Here, as will be described later with reference to FIG. 11 and the like, the correction data calculation unit 102 may include a measurement start register 224 and a measurement period register 226. Specifically, the measurement start register 224 sets the timing for starting the monitoring of the comparison result CPQ of the comparator 180, and the measurement period register 226 sets the period for monitoring the comparison result CPQ of the comparator 180.

  As a result, the timing for monitoring the comparison result CPQ used for the calculation of the correction calculation data can be adjusted. Specifically, the measurement start period shown in FIG. 2 can be adjusted by the measurement start register 224, and the measurement period can be adjusted by the measurement engine register 226. The measurement start period is a period in which the comparison result CPQ is initialized to the L level as indicated by C10 in FIG. Then, the correction data calculation unit 102 starts monitoring the comparison result CPQ at the timing when the measurement start period ends. The measurement period is a period during which the correction data calculation unit 102 outputs one gradation of the measurement gradation data MGD1 to MGDk and monitors the corresponding comparison result CPQ.

2. Multiplex drive 2.1. Configuration Example of Liquid Crystal Display Device that Performs Multiplex Drive Hereinafter, a detailed operation and a detailed configuration of the present embodiment will be described by taking as an example a case where the present embodiment performs multiplex drive in the normal operation mode. In the following, a case where the present embodiment is applied to a monochromatic liquid crystal panel used in a liquid crystal projector (projection display device) or the like will be described as an example. Note that, as will be described later with reference to FIG. The present invention can also be applied to liquid crystal panels of a plurality of colors such as RGB used for PDA (Personal Digital Assistants), liquid crystal televisions, mobile phones, car navigation systems and the like.

  FIG. 3 shows a configuration example of a liquid crystal display device (electro-optical device) including a driver 60 (integrated circuit device) to which the present embodiment is applied. The configuration example illustrated in FIG. 3 includes a liquid crystal panel 12 (electro-optical panel), a driver 60, a display controller 40, and a power supply circuit 50.

  Specifically, the liquid crystal panel 12 can be constituted by, for example, an active matrix type liquid crystal panel. At this time, a plurality of scanning lines G1 to Gm (m is an integer of 2 or more) arranged in the Y direction in FIG. 3 and extending in the X direction on the liquid crystal substrate (active matrix substrate, for example, a glass substrate) of the liquid crystal panel 12; A plurality of data lines S11 to S81, S12 to S82,..., S1n to S8n (n is an integer of 2 or more) arranged in the X direction and extending in the Y direction are arranged. The liquid crystal substrate is provided with data voltage supply lines S1 to Sn. Further, this liquid crystal substrate is provided with demultiplexers DMUX1 to DMUXn corresponding to the respective data voltage supply lines.

  Further, on the liquid crystal substrate, for example, a position corresponding to an intersection of the scanning line Gj (1 ≦ j ≦ m, j is a natural number) and the data line S1i (data lines S2i to S8i) (1 ≦ i ≦ n, i is a natural number). In addition, a thin film transistor Tji-1 (thin film transistors Tji-2 to Tji-8) is provided.

  For example, the gate electrode of Tji-1 is connected to the scanning line Gj, the source electrode is connected to the data line S1i, and the drain electrode is connected to the pixel electrode PEji-1. Between the pixel electrode PEji-1 and the counter electrode CE (common electrode, common electrode), a liquid crystal capacitor CLji-1 (liquid crystal element, electro-optical element in a broad sense) is formed. And the transmittance | permeability of a pixel changes according to the applied voltage between pixel electrode PEji-1 and counter electrode CE.

  The demultiplexer DMUXi supplies the data voltage SVi supplied to the data voltage supply line Si in a time division manner, for example, by dividing it into eight data lines S1i to S8i. The demultiplexer DMUXi separates the data voltage SVi of the data voltage supply line Si into each data line based on the multiplex control signal from the data driver 20.

  Here, in FIG. 3, only the demultiplexer DMUXi and the data lines S1i to S8i corresponding to the data voltage supply line Si are shown for the sake of simplicity. Further, only the thin film transistor provided at the position corresponding to the intersection of the data lines S1i to S8i and the scanning line Gj is shown. However, the same applies to demultiplexers and data lines corresponding to other data voltage supply lines, and thin film transistors provided at positions corresponding to intersections between other data lines and scanning lines.

  The voltage level of the counter electrode voltage VCOM applied to the counter electrode CE is generated by a counter electrode voltage generation circuit included in the power supply circuit 50. For example, the counter electrode CE is formed on one surface on the counter substrate.

  The data driver 20 drives the data voltage supply lines S1 to Sn of the liquid crystal panel 12 based on the gradation data. When the data driver 20 drives the data voltage supply lines S1 to Sn, the data driver 20 is separated and controlled by the demultiplexers DMUX1 to DMUXn as described above, so that the data driver 20 includes the data lines S11 to S81, S12 to S82,. , S1n to S8n can be driven. On the other hand, the scanning driver 38 scans (sequentially drives) the scanning lines G1 to Gm of the liquid crystal panel 12.

  The display controller 40 controls the data driver 20, the scan driver 38, and the power supply circuit 50 according to the contents set by a host such as a central processing unit (CPU) (not shown). More specifically, the display controller 40 supplies the data driver 20 and the scan driver 38 with, for example, setting of an operation mode and supply of an internally generated vertical synchronization signal and horizontal synchronization signal.

  The power supply circuit 50 generates various voltage levels (reference voltages) necessary for driving the liquid crystal panel 12 and the voltage level of the counter electrode voltage VCOM of the counter electrode CE based on a reference voltage supplied from the outside.

  In the liquid crystal display device having such a configuration, under the control of the display controller 40, the data driver 20, the scan driver 38, and the power supply circuit 50 cooperate to drive the liquid crystal panel 12 based on gradation data supplied from the outside. To do.

  In FIG. 3, an example has been described in which one pixel is composed of one dot as a liquid crystal panel for monochromatic display, and one data voltage supply line supplies a data voltage to eight data lines. In the present invention, in order to display each color component of RGB, one pixel is composed of 3 dots. For example, one data voltage supply line has six data lines and data voltages (for example, R1, R2, G1, G2, B1). , B2 (data voltage corresponding to each pixel) may be supplied.

  In FIG. 3, the liquid crystal display device includes the display controller 40, but the display controller 40 may be provided outside the liquid crystal display device. Alternatively, the host may be included in the liquid crystal display device together with the display controller 40. Further, some or all of the data driver 20, the scan driver 38, the display controller 40, and the power supply circuit 50 may be formed on the liquid crystal panel 12.

  Further, in FIG. 3, the display driver 60 may be configured as a semiconductor device (integrated circuit, IC) by integrating the data driver 20, the scan driver 38, and the power supply circuit 50.

  FIG. 4 shows a configuration example of the data driver 20 of FIG. The data driver 20 includes a shift register 22, line latches 24 and 26, a multiplexing circuit 28, a correction circuit 70, a reference voltage generation circuit 30 (grayscale voltage generation circuit), and a DAC 32 (Digital-to-Analog Converter, data in a broad sense). Voltage generation circuit), data line drive circuit 34, and multiplex drive control unit 36.

  The shift register 22 includes a plurality of flip-flops provided corresponding to the data voltage supply lines and sequentially connected. When the shift register 22 holds the enable input / output signal EIO in synchronization with the clock signal CLK, the shift register 22 sequentially shifts the enable input / output signal EIO to the adjacent flip-flops in synchronization with the clock signal CLK. The clock signal CLK and the enable input / output signal EIO are input from the display controller 40, for example.

  The line latch 24 receives gradation data (DIO) from the display controller 40 in units of 64 bits (8 bits (gradation data) × 8 (multiple number)), for example. The line latch 24 latches the gradation data (DIO) in synchronization with the enable input / output signal EIO sequentially shifted by each flip-flop of the shift register 22.

  The line latch 26 latches the grayscale data for one horizontal scan latched by the line latch 24 in synchronization with the horizontal synchronization signal LP supplied from the display controller 40.

  The multiplexing circuit 28 time-division multiplexes the gradation data for the eight data lines latched corresponding to each source line in the line latch 26. When this multiplexing circuit 28 is applied to this embodiment, it is provided between the image data registers PDR1 to PDRn and the addition circuits AD1 to ADn in the detailed configuration example shown in FIG. 8, for example.

  The correction circuit 70 corrects the variation in the data voltage using the correction data obtained by the correction data calculation method described in FIG. Specifically, correction data CD1 to CDn corresponding to the data voltage supply lines S1 to Sn are obtained in the correction data calculation mode, and the gradation data from the multiplexing circuit 28 is obtained using the correction data CD1 to CDn in the normal operation mode. Correction processing is performed, and gradation data after the correction processing is output.

  The multiplex drive control unit 36 generates multiplex control signals SEL1 to SEL8 that define the time division timing of the data voltage of the data voltage supply line. More specifically, the multiplex drive control unit 36 generates the multiplex control signals SEL1 to SEL8 so that one of the multiplex control signals SEL1 to SEL8 becomes active in order within one horizontal scanning period. The multiplexing circuit 28 multiplexes based on the multiplex control signals SEL1 to SEL8 so as to supply the data voltage to the data voltage supply line in a time division manner. The multiplex control signals SEL1 to SEL8 are also supplied to the demultiplexers DMUX1 to DMUXn of the liquid crystal panel 12.

The reference voltage generation circuit 30 generates 256 (= 2 8 ) types of reference voltages (grayscale voltages). 256 types of reference voltages (gradation voltages) generated by the reference voltage generation circuit 30 are supplied to the DAC 32.

  The DAC 32 generates an analog gradation voltage to be supplied to each data line. Specifically, the DAC 32 selects one of the reference voltages (gradation voltages) from the reference voltage generation circuit 30 based on the digital gradation data from the correction circuit 70 and corresponds to the digital gradation data. An analog gradation voltage is output, and a time division multiplexed gradation voltage is output.

  The data line driving circuit 34 buffers the grayscale voltage from the DAC 32 and outputs the data voltage as data voltages to the data voltage supply lines S1 to Sn. The data lines S11 to S81, S12 to S82,..., S1n to S8n are output. To drive. For example, the data line driving circuit 34 includes a voltage follower connection operational amplifier (impedance conversion circuit in a broad sense) provided for each data voltage supply line, and each of these operational amplifiers outputs the gradation voltage from the DAC 32. Impedance is converted and output to the data voltage supply lines S1 to Sn.

2.2. FIG. 5 is an operation explanatory diagram of the multiplex drive circuit 36 of FIG.

  FIG. 5 shows an operation example of the demultiplexer DMUXi that separates the data voltages V1 to V8 (data voltage SVi) supplied to the data voltage supply line Si by time division into the data lines S1i to S8i. It is the same.

  As shown in FIG. 5, the data line driving circuit 34 outputs multiplexed data voltages V1 to V8 corresponding to the multiplexed data multiplexed by the multiplexing circuit 28. First, the multiplexed data multiplexed by the multiplexing circuit 28 and the multiplexed gradation voltage output from the DAC 32 will be described.

  The gradation data for the first to eighth data lines (data lines S1i to S8i) latched by the line latch 26 are denoted by GD1 to GD8. The multiplex control signals SEL1 to SEL8 generated by the multiplex drive control unit 36 are signals that become active once, for example, once in one horizontal scanning period. When the multiplex control signal SEL1 becomes active, the multiplexing circuit 28 selectively outputs the gradation data GD1 for the first data line (data line S1i), and the multiplex control signal SEL2 becomes active. When the multiplex control signal SEL8 becomes active, the grayscale data GD2 for the second data line (for example, the data line S2i) is selectively output, and the eighth data line (for example, the data line S8i) is activated. Gradation data GD3 for use is selectively output. As a result, the multiplexing circuit 28 generates multiplexed data in which the grayscale data GD1 to GD8 for the first to eighth data lines are time-division multiplexed, and supplies this multiplexed data to the correction circuit 70. .

  The correction circuit 70 corrects the multiplexed data obtained by time-division multiplexing the gradation data GD1 to GD8 using the correction data CDi. For example, correction processing is performed by adding correction data CDi to each of the gradation data GD1 to GD8. Then, the corrected gradation data GD1 'to GD8' are output.

  Each decoder of the DAC 32 converts the first to eighth gradation voltages corresponding to the gradation data GD1 ′ to GD8 ′, which have been multiplexed and corrected, into a reference voltage (gradation voltage, for example, 256 gradations). ) To choose from. As a result, each decoder of the DAC 32 outputs a gradation voltage obtained by multiplexing the first to eighth gradation voltages with respect to the multiplexed data. That is, the DAC 32 generates first to eighth gradation voltages corresponding to each gradation data in which each gradation voltage is multiplexed by the multiplexing circuit 28.

  As shown in FIG. 5, the data line driving circuit 34 receives the multiplexed first to eighth grayscale voltages from the DAC and multiplexes the first to eighth data voltages V1 to V8 ( For example, the data voltage SVi) is output within one horizontal scanning period.

  The demultiplexer DMUXi uses the multiplex control signals SEL1 to SEL8 to separate the multiplexed data voltages V1 to V8 of the data voltage supply line Si and outputs the data voltages to the data lines S1i to S8i.

  More specifically, when the multiplex control signal SEL1 is active as indicated by A1 in FIG. 5, the demultiplexer DMUXi applies the multiplexed data voltage V1 indicated by A2 to the data line S1i as indicated by A3. Output. Similarly, when the multiplex control signal SEL2 is active, the multiplexed data voltage V2 is output to the data line S2i, and when the multiplex control signal SEL8 is active, the multiplexed data voltage V8 is output to the data line S8i. To do.

  In this way, a data voltage can be supplied to the TFT source connected to the selected scanning line in the liquid crystal panel 12.

2.3. Correction Data Calculation in Multiplex Drive FIG. 6 shows an operation example of correction data calculation in multiplex drive. FIG. 6 shows a case where, in the correction data calculation mode, for example, correction data CDi for the data voltage supply line Si is obtained as correction data to be calculated (correction data corresponding to the data line drive circuit to be corrected). However, the same applies when obtaining other correction data.

  For example, when the data voltage supply line Si described with reference to FIG. 5 is multiplex driving for supplying data voltages to eight data lines in one horizontal scanning period, the correction circuit 70 performs correction calculation in one horizontal scanning period in the correction data calculation mode. Measurement of the data is performed 8 times. In other words, if the first to eighth correction calculation data measurements are defined as the first to eighth indexes, the correction calculation data described with reference to FIG. Eighth correction calculation data is obtained.

  Specifically, as indicated by B1, when the multiplex control signal SEL1 is active, the correction circuit 70 performs measurement at the first index. In the first index, the correction circuit 70 outputs, for example, measurement gradation data MGD1 to MGD8 (measurement data MD). The DAC 32 selects and outputs the gradation voltage corresponding to each measurement gradation data of the measurement gradation data MGD1 to MGD8 from the reference voltage (gradation voltage). 5, the data line driving circuit 34 receives the gradation voltage from the DAC 32 and outputs the data voltages CV1 to CV8 corresponding to the measurement gradation data MGD1 to MGD8 to the data voltage supply line Si. To do. At this time, as indicated by B3, the demultiplexer DMUXi outputs the data voltages CV1 to CV8 to the data line S1i based on the multiplex signal SEL1. The correction circuit 70 compares the data voltages CV1 to CV8 output to the data voltage supply line Si with the comparator reference voltage VP by, for example, the comparator 180 in FIG. 1, and the comparison result CPQ is inverted (for example, from L level to H level). ) Is used to obtain the first correction calculation data.

  Similarly, the correction circuit 70 obtains the second to eighth correction calculation data at the second to eighth indexes, and averages the first to eighth correction calculation data, for example, to obtain the correction data CDi. Ask.

  Thus, according to the present embodiment, the output variation of the data line driving circuit is repeatedly measured in one horizontal scanning period. Thereby, the influence of the measurement mistake by noise etc. can be decreased. Further, according to the present embodiment, as described with reference to FIG. 6, the data for correction calculation is obtained by driving the data lines in a time division manner in the same manner as in the multiplex driving in one horizontal scanning period. Thus, the data line can be driven with the same accuracy in the normal operation mode and the correction data calculation mode, and the data voltage can be corrected accurately.

  6 illustrates an example in which the correction circuit 70 outputs the measurement gradation data MGD1 to MGD8 (k = 8) as the measurement gradation data. However, the correction circuit 70 has another number of measurement floors. The tone data may be output, and the data line driving circuit 34 may output the same number of corresponding data voltages.

2.4. Correction Coefficient FIG. 7 is an explanatory diagram of the correction coefficient that is multiplied by the correction data. FIG. 7 shows the data voltage SVi in one of the first to eighth indexes described in FIG.

  At this time, the data line driving circuit 34 outputs the data voltage SVi to the data voltage supply line Si to drive any of the data lines S1i to S8i. For example, one of the data lines S1i to S8i is driven by an operational amplifier OPi described later with reference to FIG.

  As shown in LD1 of FIG. 7, when the operational amplifier OPi has a sufficient capability (speed) for driving the data line, the data line becomes sufficient as the correction circuit 70 outputs the measurement gradation data MGD1 to MGD8. Driven to reach the desired data voltage. As indicated by D1, for example, when the data voltage corresponding to the measurement gradation data MGD5 is larger than the comparator reference voltage VP, the correction circuit 70 uses the measurement gradation data MGD5 as the correction gradation data. Here, for simplicity, it is assumed that the measurement gradation data MGD5 is measured as the correction gradation data in the other indexes, and the measurement gradation data MGD5 is obtained as the correction data CDi.

  On the other hand, in multiplex driving, it is necessary to measure a plurality of correction calculation data in one horizontal scanning period and drive the data lines with data voltages corresponding to the plurality of measurement gradation data in one measurement. The operational amplifier OPi may not have sufficient ability (speed) to drive the data line. At this time, as indicated by LD2, the data line is not sufficiently driven as compared with the data line voltage indicated by LD1, and the desired data voltage is not reached. As shown in D2, for example, when the data voltage corresponding to the measurement gradation data MGD6 is larger than the comparator reference voltage VP, the measurement gradation data MGD5 is used as the correction gradation data. Similarly, in other indexes, the measurement gradation data MGD6 is measured as the correction gradation data, and the measurement gradation data MGD6 is obtained as the correction data CDi.

  Thus, when the driving power of the operational amplifier is insufficient, correction data having a value deviated from the correction data calculated in an ideal case where the driving power of the operational amplifier is sufficient is calculated. Therefore, the deviation from the correction data calculated in the ideal case of the operational amplifier driving force is corrected by multiplying the correction data actually calculated by the correction coefficient.

3. Detailed configuration example 3.1. Detailed Configuration Example of the Present Embodiment FIG. 8 shows a detailed configuration example of the present embodiment. In the following, each component such as the comparator described with reference to FIG. Further, the present embodiment is not limited to the configuration of FIG. 8, and various modifications such as omitting a part of the configuration (for example, a shift register, a data switching circuit, etc.) or adding other components are possible. is there.

  The configuration example of FIG. 8 includes switches SW1 to SWn, shift registers SR1 to SRn, operational amplifiers OP1 to OPn, D / A conversion circuits DAC1 to DACn (Digital to Analog Converter, data voltage generation circuit in a broad sense), selectors DS1 to DSn. (Data switching circuit), addition circuits AD1 to ADn (correction processing circuit in a broad sense), correction data registers CDR1 to CDRn, image data registers PDR1 to PDRn, a comparator 180, a control unit 100, and a correction data calculation unit 102.

  The image data registers PDR1 to PDRn hold image data PD1 to PDn that are gradation data corresponding to pixels driven by the data voltage supply lines S1 to Sn. For example, the image data PD1 to PDn may be collectively written to the image data registers PDR1 to PDRn from the image data stored in a storage unit such as a RAM (Random Access Memory), and stream data is received by the I / F circuit. The image data registers PDR1 to PDRn may be sequentially written.

  The correction data registers CDR1 to CDRn hold the measurement data MD and the correction data CD1 to CDn from the correction data calculation unit 102. For example, when correction data CDi is calculated in the correction data calculation mode, measurement data MD sequentially output from the correction data calculation unit 102 is set in the correction data register CDRi, and the correction data register CDRi selects the correction data MD as a selector. Output to DSi. Then, the correction data calculation unit 102 calculates correction data CDi by calculating correction data, and sets the correction data CDi in the correction data register CDRi. In the normal operation mode, the correction data register CDRi outputs the correction data CDi to the addition circuit ADi. Measurement data and correction data are set in the correction data registers CDR1 to CDRn, for example, when the outputs of the corresponding shift registers SR1 to SRn are active.

  Note that initial values may be set in the correction data registers CDR1 to CDRn. For example, as described in FIG. 10, the initial values of the correction data CD1 to CDn may be set by the burst mode, or the initial values of the correction data CD1 to CDn may be set from a host controller (not shown).

  The adder circuits AD1 to ADn add the correction data CD1 to CDn to the image data PD1 to PDn, perform correction processing, and output the corrected image data PCD1 to PCDn. The correction processing may be performed by adding correction data CD1 to CDn to the image data PD1 to PDn and performing correction processing, or by adding or multiplying other coefficients.

  The selectors DS1 to DSn receive the measurement data MD from the correction data registers CDR1 to CDRn and the image data PCD1 to PCDn from the adder circuits AD1 to ADn, select one of them and send it to the D / A conversion circuits DAC1 to DACn. Output. Specifically, the selectors DS1 to DSn select data based on the correction enable signal C_Enable from the control circuit 100. For example, in the correction data calculation mode, the control unit 100 activates the correction enable signal C_Enable, and the selectors DS1 to DSn select and output the measurement data MD. On the other hand, in the normal operation mode, the control unit 100 deactivates the correction enable signal C_Enable, and the selectors DS1 to DSn select and output the image data PCD1 to PCDn.

  The D / A conversion circuits DAC1 to DACn generate gradation voltages to be supplied to the data voltage supply lines S1 to Sn. Specifically, based on the gradation data (measurement data MD or image data PCD1 to PCDn) from the selectors DS1 to DSn, one of the reference voltages is selected and the gradation voltage is output. More specifically, the gradation voltage corresponding to the measurement data MD is output in the correction data calculation mode, and the gradation voltage corresponding to the image data PCD1 to PCDn is output in the normal operation mode. When the present embodiment performs multiplex driving, the D / A conversion circuits DAC1 to DACn output grayscale data time-division multiplexed based on the image data PCD1 to PCDn in which the grayscale data is time-division multiplexed. To do. Note that the reference voltage is input from, for example, a reference voltage generation circuit 30 shown in FIG.

  The operational amplifiers OP1 to OPn buffer the grayscale voltages from the D / A conversion circuits DAC1 to DACn and output the data voltages S1 to Sn to the data voltage supply lines S1 to Sn. For example, as shown in FIG. 8, a voltage follower can be configured using operational amplifiers OP1 to OPn to buffer gradation voltages.

  Shift registers SR1 to SRn output switch control signals SRQ1 to SRQn for controlling on / off of switches SR1 to SRn. Specifically, switch control that takes in H_SR (first logic level) SR_Data from the control unit 100, sequentially shifts H_SR_Data based on SR_Clock from the control unit 100, and sequentially becomes active. Output a signal. For example, when calculating the correction data CDi in the correction data calculation mode, the shift register SRi outputs active as the switch control signal SRQi.

  The switches SW1 to SWn are turned on / off based on signals from the shift registers SR1 to SRn. Specifically, the switches SW1 to SWn are turned on when signals from the shift registers SR1 to SRn are active, and are turned off when inactive. For example, when the correction data CDi is obtained in the correction data calculation mode, the switch SWi is turned on and the data voltage SVi output from the operational amplifier OPi is input to the comparator 180 as the comparator input voltage CPI.

  The control unit 100 includes shift data SR_Data, a reset signal SR_Reset for the shift registers SR1 to SRn, a clock SR_Clock for the shift registers SR1 to SRn to capture shift data, and an enable signal that determines a period during which the shift registers SR1 to SRn output active. SR_Enable and selectors DS1 to DSn output a correction enable signal C_Enable for outputting measurement data MD in the correction data calculation mode.

3.2.1 H Mode A detailed operation example of the present embodiment will be described with reference to FIGS. 9 and 10. In the present embodiment, correction data calculation is performed in the 1H mode and the burst mode as the correction data calculation mode.

  FIG. 9 shows a signal waveform example in the 1H mode.

  In the present embodiment, correction data calculation in the 1H mode is performed in one horizontal scanning period of the non-display period. Specifically, correction data calculation in the 1H mode is performed in each of the first to nth vertical scanning periods of the plurality of vertical scanning periods (frames).

  More specifically, as indicated by E1 in FIG. 9, the correction data calculation unit 102 calculates the correction data CD1 in one horizontal scanning period within the first vertical scanning period.

  At this time, the control unit 100 activates SR_Reset as indicated by E2 to reset the shift registers SR1 to SRn, and deactivates the outputs of the shift registers SR1 to SRn as indicated by E3.

  Next, the control unit 100 outputs an H level (first logic level) to SR_Data as indicated by E4, and the SR_Clock from the control unit 100 indicated by E5 causes the shift register SR1 to be at the H level of SR_Data as indicated by E6. Capture levels.

  As indicated by E7, the control unit 100 activates SR_Enable, and the shift register SR1 outputs active as the switch control signal SRQ1 in the active period of SR_Enable.

  Then, the switch SW1 is turned on in response to the active switch control signal SRQ1 as indicated by E8, and the data voltage SV1 is input to the comparator 180 as the comparator input CPI as indicated by E9.

  The correction data calculation unit 102 sequentially outputs the measurement data MD in the 1H mode indicated by E1. As indicated by E 10, when the control unit 100 activates C_Enable, the data voltage SV 1 corresponding to the measurement data MD is output to the data voltage supply line S 1 and input to the comparator 180. The correction data calculation unit 102 receives the comparison result CPQ from the comparator 180, for example, performs edge detection with the edge detection unit 260 in FIG. 11, and obtains correction data CD1. The correction data calculation unit 102 sets the obtained correction data CD1 in the correction data register CDR1.

  In this way, the correction data calculation unit 102 obtains the correction data CD1 in the 1H mode in the first vertical scanning period indicated by E1. Similarly, the correction data CD2 is obtained and set in the correction data register CDR2 in the 1H mode in the subsequent second vertical scanning period as indicated by E11, and the correction data in the 1H mode in the nth vertical scanning period as indicated by E12. CDn is obtained and set in the correction data register CDRn. Then, in the subsequent (n + 1) th vertical scanning period, the correction data CD1 is obtained again and set in the correction data register CDR1, and the correction data CD1 to CDn held in the correction data registers CDR1 to CDRn are sequentially updated by repeating this.

  As shown in E13, the present embodiment performs image display in the normal operation mode between the 1H mode and the 1H mode. Specifically, in the present embodiment, image data is corrected with correction data obtained in the 1H mode, and image display is performed.

  As described above, by performing correction data calculation in the 1H mode every vertical scanning period, variations in the data voltages SV1 to SVn due to offsets of the operational amplifiers OP1 to OPn can be corrected in real time. Further, by performing correction data calculation during a non-display period within the vertical scanning period, correction data can be calculated without affecting image display.

  According to the present embodiment, the correction data calculation unit 102 can also limit the amount of change in the correction data. For example, as shown in FIG. 9, it is assumed that the correction data calculation unit 102 obtains one correction data in one vertical scanning period and sequentially obtains correction data CD1 to CDn. Then, when the correction data CDi (current correction data) is obtained in the 1H mode in the vertical scanning period with the correction data calculation unit 102, the correction data CDi (previous correction data) obtained in the 1H mode in the n-th vertical scanning period. ) Can be limited to a positive or negative predetermined value. Thereby, it is possible to prevent the image quality from deteriorating due to abrupt changes in correction data due to noise or the like.

  The non-display period in which the present embodiment executes the 1H mode is a period in which the data line driving circuits 140-1 to 140-n do not output the data voltages SV1 to SVn corresponding to the image data PD1 to PDn. For example, it is a period from the fall of the vertical synchronization signal Vsync to the start of input of the image data PD1 to PDn to the image data registers PDR1 to PDRn. Alternatively, it is a period from the fall of the vertical synchronization signal Vsync until the first scanning line (for example, the scanning line G1 in FIG. 3) of the liquid crystal panel (for example, the liquid crystal panel 12 in FIG. 3) is selected.

3.3. Burst Mode FIG. 10 shows a signal waveform example in the burst mode.

  In the present embodiment, correction data calculation is performed in a burst mode in which initial values of the correction data CD1 to CDn are collectively obtained during the display preparation period. Specifically, as shown in F1 of FIG. 10, the initial values of the correction data CD1 to CDn are obtained in the burst mode, and the correction data CD1 to CDn are obtained in the 1H mode after the burst mode as shown in F2.

  For example, in the present embodiment, the burst mode is executed during a period in which image display is not performed when the system is started up. For example, the burst mode is executed when an electronic device (projector, car navigation system, PDA, etc.) is turned on or returned from a hibernation state, before the backlight or projector lamp is turned on. Or this embodiment performs burst mode in the period when the image display at the time of display mode switching is not performed. For example, the burst mode is executed when the resolution of image display is switched.

  In the burst mode shown in FIG. 10, the present embodiment obtains initial values of the correction data CD1 to CDn in the first to nth horizontal scanning periods among the plurality of horizontal scanning periods.

  Specifically, first, as indicated by F3, the control unit 100 activates SR_Reset to reset the shift registers SR1 to SRn.

  Next, the control unit 100 outputs an H level (first logic level) to SR_Data as indicated by F4, and the SR_Clock from the control unit 100 indicated by F5 causes the shift register SR1 to be H of SR_Data as indicated by F6. Capture levels.

  As indicated by F7, the control unit 100 activates SR_Enable, and the shift register SR1 outputs active as the switch control signal SRQ1 in the active period of SR_Enable.

  Then, the switch SW1 is turned on in response to the active switch control signal SRQ1 as indicated by F8, and the data voltage SV1 is input to the comparator 180 as the comparator input CPI as indicated by F9.

  As indicated by F10, when the control unit 100 activates C_Enable, the data voltage SV1 corresponding to the measurement data MD is output to the data voltage supply line S1, and is input to the comparator 180. The correction data calculation unit 102 receives the comparison result CPQ from the comparator 180, obtains correction data CD1, and sets it in the correction data register CDR1 as an initial value.

  In this way, the correction data calculation unit 102 obtains the initial value of the correction data CD1 in the first horizontal period in the burst mode. Similarly, the initial value of the correction data CD2 is obtained and set in the correction data register CDR2 in the subsequent second horizontal scanning period, and the initial value of the correction data CDn is obtained and set in the correction data register CDRn in the nth horizontal scanning period. To do. Then, after obtaining the initial values of the correction data CD1 to CDn in the burst mode, the correction data CD1 to CDn are sequentially updated every vertical scanning period in the 1H mode.

  Note that the control unit 100 does not reset the shift registers SR1 to SRn and outputs an L level (second logic level) to SR_Data during the horizontal scanning period in which the correction data CD2 to CDn are calculated.

  By the way, when the initial values of the correction data CD1 to CDn are not set, the variation in the data line voltage is not corrected until the correction data CD1 to CDn is calculated in the 1H mode, so that the display image immediately after the power is turned on or the like. There is a problem that image quality deteriorates.

  In this regard, according to the present embodiment, the initial values of the correction data CD1 to CDn are set in the correction data registers CDR1 to CDRn before the 1H mode is executed. Thus, the variation in the data line voltage can be corrected by the initial value until the first correction data CD1 to CDn are updated in the 1H mode. For example, as shown in F11 of FIG. 10, when the correction data CD1 is obtained in the first 1H mode (F2) after the burst mode, the correction data obtained in the 1H mode in the normal operation mode after the first 1H mode. Correction can be made with the initial values CD2 to CDn obtained in CD1 and burst mode.

  Further, according to the present embodiment, the burst mode is executed during a display preparation period such as when the power is turned on or before the backlight is turned on. As a result, the image quality can be improved by correcting the data voltage variation immediately after the start of the image display without affecting the image display.

  Here, in the present embodiment, in the display preparation period or the non-display period, the data voltage supply lines S1 to Sn are set to a predetermined data voltage in the first horizontal scanning period among the plurality of horizontal scanning periods, and the subsequent second In the horizontal scanning period, the correction data calculation unit 102 may obtain the correction data CD1 to CDn.

  For example, after the data voltage supply lines S1 to Sn are set to a predetermined data voltage in one horizontal scanning period in the non-display period indicated by E14 in FIG. 9, the 1H mode indicated by E1 may be executed. The burst mode shown in F1 may be executed after the data voltage supply lines S1 to Sn are set to a predetermined data voltage in one horizontal scanning period in the display preparation period shown in F12.

  As the predetermined data voltage, for example, when the correction data calculation unit 102 sequentially changes the measurement data MD, a voltage within a range in which the corresponding data voltage changes is set. For example, the operational amplifiers OP1 to OPn may output the predetermined data voltage by setting the gradation data corresponding to the predetermined data voltage in the correction data registers CDR1 to CDRn.

  As described above, according to the present embodiment, the data voltage supply lines S1 to Sn to which various data voltages are output depending on the data voltage of the display image or the like are fixed in one horizontal scanning period before the correction data calculation. Set to voltage. Thereby, it is possible to measure the variation in the data voltage by starting from the same data voltage every time the correction data calculation is started. Therefore, the variation in data voltage can be measured with the same accuracy every time, and correction data that accurately reflects the variation in data voltage can be obtained.

3.4. Detailed Configuration Example of Control Unit and Correction Data Calculation Unit FIG. 11 shows a detailed configuration example of the control unit and the correction data calculation unit. 11 includes a correction data calculation unit 102 and a sequencer 240, and the correction data calculation unit 102 includes a counter unit 200, a register unit 220, an edge detection unit 260, and a processing unit 280. The correction data calculation unit 102 according to the present embodiment is not limited to the configuration shown in FIG. 11, and various modifications such as omitting some of the configuration requirements (index register 222, interval register 228, etc.) are possible.

  The counter unit 200 includes an index counter 202, a measurement start counter 204, a measurement period counter 206, an interval counter 208, and a measurement data counter 210.

  The index counter 202 counts an index that is the number of times correction correction data is measured in one horizontal scanning period. For example, the index counter 202 increments the index according to an instruction from the sequencer 240.

  The measurement start counter 204 counts the measurement start period from the horizontal synchronization signal to the start of correction data calculation. For example, the measurement start counter 204 counts the measurement start period using the dot clock Dclk.

  The measurement period counter 206 counts a period during which the comparator 180 compares the data voltage corresponding to one measurement data when the correction data calculation unit 102 sequentially outputs the measurement data MD (measurement gradation data). . For example, the measurement period counter 206 counts the measurement period based on the dot clock Dclk.

  The interval counter 208 counts the interval period from the end of one index to the start of the next index. The interval period is a period for initializing the output of the comparator 180 (comparison result CPQ) (for example, initializing to L level). For example, the interval counter 208 counts the interval period using the dot clock Dclk.

  The measurement data counter 210 generates measurement data MD based on the count value. For example, the measurement data counter 210 increments the count value every measurement period in accordance with an instruction from the sequencer 240.

  The register unit 220 includes an index register 222, a measurement start register 224, a measurement period register 226, an interval register 228, and a correction calculation data register 230.

  The index register 222 sets the number of indexes counted by the index counter 202.

  The measurement start register 224 sets a measurement start period counted by the measurement start counter 204.

  The measurement period register 226 sets the measurement period counted by the measurement period counter 206.

  The interval register 228 sets an interval period counted by the interval counter 208.

  For example, register values are set in the index register 222, the measurement start register 224, the measurement period register 226, and the interval register 228 from a host controller (CPU) (not shown).

  The correction calculation data register 230 holds correction calculation data calculated at each index. For example, the correction calculation data register 230 receives the edge detection pulse from the edge detection unit 260 and holds the measurement gradation data from the measurement data counter 210. Alternatively, the correction calculation data register 230 holds the correction calculation data subjected to the correction exception process from the processing unit 280.

  The edge detector 260 receives the comparison result CPQ from the comparator 180 and outputs an edge detection pulse. For example, as described with reference to FIG. 2, a rising edge (falling edge) of the comparison result CPQ is detected and an edge detection pulse is output.

  The processing unit 280 calculates correction data CD1 to CDn from the correction calculation data of each index held in the correction calculation data register 230, and sets the correction data in the correction data registers CDR1 to CDRn. For example, the processing unit 280 calculates correction data by averaging the correction calculation data of each index.

  Further, the processing unit 280 performs correction exception processing on the correction calculation data. The processing unit 280 can multiply the correction coefficient as the correction exception process. Specifically, as described with reference to FIG. 7 and the like, the measured correction calculation data is multiplied by a predetermined correction coefficient and set in the correction calculation data register 230. Further, the processing unit 280 can perform overflow processing as correction exception processing. Specifically, the processing unit 280 sets the overflow data in the correction calculation data register 230 when it is determined that overflow has occurred in the measurement of the correction calculation data. Further, the processing unit 280 can limit the amount of change as the correction exception process. Specifically, for example, the amount of change in the correction data is limited using the previous correction data held in the correction data registers CDR1 to CDRn in FIG.

  When the present embodiment alternately drives the data lines in the positive polarity period and the negative polarity period in the normal operation mode, the processing unit 280 corrects the correction data for the positive polarity and the correction for the negative polarity from the correction calculation data. You can also ask for data. For example, the processing unit 280 may use the 2's complement of the positive polarity correction data as the negative polarity correction data, or may use a 1's complement.

  The sequencer 240 receives the vertical synchronization signal Vsync, the horizontal synchronization signal Hsync, and the dot clock Dclk, controls the correction data calculation unit 102, the shift data SR_Data described in FIGS. 8 to 10, the reset signal SR_Reset of the shift register, and the shift The register clock SR_Clock, the shift register output enable signal SR_Enable, and the correction enable signal C_Enable are output.

  The correction data calculation unit 102 and the sequencer 240 may be configured using, for example, a gate array, and are realized by a CPU (not shown) executing a program in which the functions of the correction data calculation unit 102 and the sequencer 240 are described. May be.

  FIG. 12 shows an example of a processing flow of the correction data calculation unit 102. In FIG. 12, the operation in the 1H mode in the correction data calculation mode will be described as an example. In the burst mode, the process starts from the wait for the correction data calculation mode (step SA1) in FIG. 12 and stores the correction data (step SA22) in the same manner as in the 1H mode, and each horizontal scanning period starts from the next horizontal scanning period. Every time HSYNC wait (step SA3) to correction data storage (step SA22), this is repeated until correction data CD1 to CDn are obtained.

  The correction data calculation unit 102 waits for a correction data calculation start instruction from the sequencer 240 in the correction data calculation mode wait (SA1). If No, the correction data calculation mode wait (SA1) is repeated, and if Yes, the VSYNC wait (SA2) is performed.

  In the VSYNC wait (SA2), it waits for the edge (falling edge or rising edge) of the vertical synchronization signal Vsync. If No, the VSYNC wait (SA2) is repeated, and if Yes, the HSYNC wait (SA3) is performed.

  In the HSYNC wait (SA3), it waits for an edge (falling edge or rising edge) of the horizontal synchronization signal Hsync. If No, the HSYNC wait (SA3) is repeated, and if Yes, the measurement start counter is reset, the measurement data counter is reset, and the index counter is reset (SA4).

  Next, in the measurement start wait (SA5), it is determined whether or not the count value of the measurement start counter matches the measurement start period set in the measurement start register 224. If they do not match (No), the measurement start counter is incremented (SA6) and the measurement start wait (SA5) is repeated. If they match (Yes), the measurement period counter is reset (SA7), and a correction level match determination (SA8) is performed.

  In the correction level coincidence determination (SA8), based on the comparison result CPQ from the comparator 180, it is determined whether the data voltage output from the data line driving circuit to be corrected matches the comparator reference voltage VP. If they match (Yes), the correction calculation data is stored in the correction calculation data register 230 in the correction calculation data storage (step SA9), the index counter is incremented (SA16), and steps SA17 to SA22 are performed. If they do not match (No), the measurement period counter is incremented (SA10), and the measurement period end wait (SA11) is performed.

  In the measurement period end wait (SA11), it is determined whether or not the count value of the measurement period counter 206 matches the measurement period set in the measurement period register 226. If they do not match (No), a correction level match determination (SA8) is performed. If they match (Yes), the measurement data counter is incremented (SA12), and the measurement data maximum value determination (SA13) is performed.

  In the measurement data maximum value determination (SA13), it is determined whether or not the count value of the measurement data counter 210 exceeds a predetermined maximum value (or minimum value). If not exceeded (No), the measurement period counter is reset (SA7) and steps SA8 to SA13 are performed. When it exceeds (Yes), correction exception processing (SA14) is performed.

  In the correction exception processing (SA14), overflow processing, correction coefficient multiplication, and change amount limitation are performed, and in the correction calculation data storage (SA15), the correction calculation data is set in the correction calculation data register 230.

  Next, the index counter is incremented (SA16).

  Subsequently, the interval counter is reset (SA17) and waits for the end of the interval (SA18).

  In the interval end wait (SA18), it is determined whether or not the count value of the interval counter matches the interval period of the interval register 228. If they do not match (No), the interval counter is incremented (SA19) and the interval end wait (SA18) is repeated. If they match (Yes), the process waits for the specified number of times (SA20).

  In waiting for the end of the specified number of times (SA20), it is determined whether or not the count value of the index counter 202 matches the number of indexes set in the index register 222. If they do not match (No), the measurement period counter is reset (SA7), and steps SA8 to SA20 are performed. If they match (Yes), the correction calculation data is averaged (SA21) to obtain correction data, and correction data storage (SA22) is performed.

  In the correction data storage (SA22), for example, correction data from the processing unit 280 is set in the correction data registers CDR1 to CDRn in FIG.

  FIG. 13 shows a modification of the processing flow of the correction data calculation unit 102. The modification shown in FIG. 13 is an example of a processing flow when the present embodiment does not perform multiplex driving. Specifically, this embodiment is an example of a processing flow in the case where one data line is driven in one horizontal scanning period in the normal operation mode and one correction calculation data is obtained in one horizontal scanning period in the correction data calculation mode. is there.

  In the modification shown in FIG. 13, the index counter 202, interval counter 208, index register 222, and interval register 228 shown in FIG. 11 can be omitted.

  In the modification shown in FIG. 13, the correction data calculation unit 102 waits for a correction data calculation mode (SB1). If No, the correction data calculation mode wait (SB1) is repeated, and if Yes, the VSYNC wait (SB2) is performed.

  In the VSYNC wait (SB2), if No, the VSYNC wait (SB2) is repeated, and if Yes, the HSYNC wait (SB3) is performed.

  In the HSYNC wait (SB3), if No, the HSYNC wait (SB3) is repeated, and if Yes, the measurement start counter is reset and the measurement data counter is reset (SB4).

  Next, a measurement start wait (SB5) is performed. If No, the measurement start counter is incremented (SB6) and the measurement start wait (SB5) is repeated. In the case of Yes, the measurement period counter is reset (SB7), and the correction level coincidence determination (SB8) is performed.

  In the correction level match determination (SB8), if they match (Yes), correction calculation data storage (step SB9) is performed, and correction data calculation (SB16) is performed. If they do not match (No), the measurement period counter is incremented (SB10), and the measurement period end wait (SB11) is performed.

  In the measurement period end waiting (SB11), in the case of No, a correction level coincidence determination (SB8) is performed. In the case of Yes, the measurement data counter is incremented (SB12), and the measurement data maximum value determination (SB13) is performed.

  If the measurement data maximum value determination (SB13) is No, the measurement period counter is reset (SB7), and steps SB8 to SB13 are performed. In the case of Yes, correction exception processing (SB14) is performed, and correction calculation data storage (SB15) is performed.

  Next, in the correction data calculation (SB16), the processing unit 280 obtains correction data from the correction calculation data. For example, the processing unit 280 may use the correction calculation data stored in the correction calculation data register 230 as it is as correction data, and obtain correction data by adding or subtracting a predetermined constant to the correction calculation data. Also good.

  Then, the correction data is stored in the correction data register (SB17).

4). Layout FIG. 14 schematically shows a layout arrangement example of the present embodiment. In FIG. 14, the layout arrangement is described using the first direction D1 to the fourth direction D4, the direction opposite to the first direction D1 is defined as the second direction D2, and the direction orthogonal to the first direction D1 is defined as the direction. Let it be the third direction D3 and the fourth direction D4.

  The layout arrangement example shown in FIG. 14 includes data line driving circuits 140-1 to 140-n (a plurality of data line driving circuits) and a comparator 180.

  As shown in FIG. 14, the data line driving circuits 140-1 to 140-n are arranged along the first direction D1. The comparator 180 is arranged in the first direction D1 (or the second direction D2) of the data line driving circuits 140-1 to 140-n. Specifically, the data line driving circuits 140-1 to 140-n are arranged at equal intervals without including other components such as the comparator 180 therebetween.

  Furthermore, the layout arrangement example shown in FIG. 14 can include a gate array GA. The gate array GA includes a control unit 100 including a correction data calculation unit 102. The gate array GA can also include, for example, an I / F circuit that receives stream data and digital cells of the scan driver 38. As shown in FIG. 14, the gate array GA may be arranged in the direction D1 of the data line driving circuits 140-1 to 140-n and the comparator 180, or may be arranged in the direction D2. Further, the gate array GA may be disposed in the direction D3 or the direction D4 of the data line driving circuits 140-1 to 140-n and the comparator 180.

  Here, if the data line driving circuits 140-1 to 140-n are arranged at unequal intervals, the process processing accuracy of each data line driving circuit is not uniform. For this reason, manufacturing variations tend to occur in the output characteristics of the data line driving circuit, and there is a problem that variations in data line voltages increase.

  For example, as shown in FIG. 8, when the data voltage is output using the operational amplifiers OP1 to OPn, if the processing accuracy of the differential pair of each operational amplifier is not uniform, the offset varies and the data line voltage varies greatly. There is a problem of becoming.

  In this regard, according to the present embodiment, the data line driving circuit is arranged along the direction D1, and the comparator 180 is arranged in the direction D1 (or direction D2) of the data line driving circuit. As a result, the data line driving circuits can be arranged at equal intervals, and variations in data voltage due to manufacturing variations can be suppressed.

  Further, according to the present embodiment, data voltage variation is measured using one comparator. Thereby, it is not necessary to mix other components between the data line driving circuits, and the data line driving circuits can be arranged at equal intervals.

  As described above, according to the present embodiment, variation in data voltage due to manufacturing variation can be suppressed, and correction accuracy for correcting data voltage variation due to correction data can be improved.

5). Electronic equipment 5.1. Projector FIG. 15 shows a configuration example of a projector (electronic device) to which the integrated circuit device of this embodiment is applied.

  The projector 700 (projection display device) includes a display information output source 710, a display information processing circuit 720, a driver 60 (display driver), a liquid crystal panel 12 (electro-optical panel in a broad sense), a clock generation circuit 750, and a power supply circuit 760. Including.

  The display information output source 710 includes a ROM (Read Only Memory) and a RAM (Random Access Memory), a memory such as an optical disk device, a tuning circuit that tunes and outputs an image signal, and the like. Based on this, display information such as an image signal in a predetermined format is output to the display information processing circuit 720.

  The display information processing circuit 720 can include an amplification / polarity inversion circuit, a phase expansion circuit, a rotation circuit, a gamma correction circuit, a clamp circuit, and the like.

  The driver 60 includes a scanning driver (gate driver) and a data driver (source driver), and drives the liquid crystal panel 12 (electro-optical panel).

  The power supply circuit 760 supplies power to each circuit described above.

5.2. PDA
FIG. 16 shows a configuration example of a PDA (electronic device) to which the integrated circuit device of this embodiment is applied.

  PDA 900 (Personal Digital Assistants) includes a camera module 910, a modem unit 950, a display controller 40, a host 940 (host controller, CPU), an operation input unit 970, a driver 60 (display driver), a power supply circuit 50, and a liquid crystal panel 12 (electrical). Optical panel).

  The camera module 910 includes a CCD camera and supplies image data captured by the CCD camera to the display controller 40 in, for example, a YUV format.

  The driver 60 includes a scan driver 38 (gate driver) and a data driver 20 (source driver). The scanning driver 38 drives a plurality of scanning lines (gate lines) included in the liquid crystal panel 12. The data driver 20 drives a plurality of data lines (source lines) included in the liquid crystal panel 12.

  The display controller 40 supplies, for example, RGB format gradation data to the data driver 20, and supplies, for example, a horizontal synchronization signal to the scan driver 38.

  The power supply circuit 50 supplies a driving power supply voltage to the source driver 20 and the gate driver 38. Further, the counter electrode voltage VCOM is supplied to the counter electrode of the display panel 12.

  The host 940 controls the display controller 40. In addition, the host 940 demodulates the modulation signal received via the antenna 960 by the modulation / demodulation unit 950 to generate gradation data, and then supplies the gradation data to the display controller 40. The host 940 modulates the gradation data generated by the camera module 910 by the modulation / demodulation unit 950 and then instructs transmission to another communication apparatus via the antenna 960. Furthermore, the host 940 performs gradation data transmission / reception processing, imaging of the camera module 910, and display processing of the display panel 12 based on operation information from the operation input unit 970.

  Although the present embodiment has been described in detail as described above, it will be easily understood by those skilled in the art that many modifications can be made without departing from the novel matters and effects of the present invention. Accordingly, all such modifications are intended to be included in the scope of the present invention. For example, in the specification or the drawings, terms (electro-optical panel, inverting input terminal, non-inverting input terminal, gradation voltage, VGMH, VGML, etc.) described at least once together with different terms () having a broader meaning or the same meaning are as follows: The different terms can be used anywhere in the specification or drawings. In addition, the configurations and operations of the reference voltage generation circuit, selection circuit, sample hold unit, data line drive circuit, gradation generation amplifier, drive amplifier, electro-optical device, electronic device, and the like are also limited to those described in this embodiment. However, various modifications can be made.

Configuration example of this embodiment FIG. 2A shows an example of the voltage waveform of the data voltage in the correction data calculation mode. FIG. 2B is a voltage waveform example of a comparison result in the correction data calculation mode. Configuration example of liquid crystal display Data driver configuration example Example of voltage waveform of data line in multiplex drive Example of voltage waveform of data line in correction data calculation mode Explanation of correction factor Detailed configuration example of this embodiment Example of 1H mode signal waveform Example of signal waveform in burst mode Detailed configuration example of control unit and correction data calculation unit Control flow example of correction data calculation unit Modification of control flow of correction data calculation unit Layout layout example of this embodiment Example of projector configuration Configuration example of PDA

Explanation of symbols

12 electro-optic panel, 20 data driver, 22 shift register,
24 line latch, 28 multiplexing circuit, 30 reference voltage generating circuit, 32 DAC,
34 data line drive circuit, 36 multiplex drive control unit, 38 scan driver,
40 display controller, 50 power supply circuit, 60 driver, 100 control unit,
102 correction data calculation unit, 120 selection circuit,
140-1 to 140-n first to n-th data line driving circuits,
160-1 to 160-n 1st to n-th correction circuits, 180 comparators,
200 counter section, 202 index counter, 204 measurement start counter,
206 measurement period counter, 208 interval counter,
210 data counter for measurement, 220 register section, 222 index register,
224 measurement start register, 226 measurement period register,
228 interval register, 230 correction calculation data register,
240 sequencer, 260 edge detection unit, 280 processing unit,
700 projector, 710 display information output source, 720 display information processing circuit,
750 clock generation circuit, 760 power supply circuit, 900 PDA,
910 camera module, 940 host, 950 modulation / demodulation unit, 970 operation input unit,
VP comparator reference voltage, CPQ comparison result, MD measurement data,
CD1-CDn correction data, PD1-PDn image data,
PCD1-PCDn image data after correction processing,
MGD1 to MGDk measurement gradation data,
S1-Sn data voltage supply line, SV1-SVn data voltage,
Vsync vertical sync signal, Hsync horizontal sync signal, Dclk dot clock

Claims (15)

  1. A plurality of data line driving circuits for driving a plurality of data voltage supply lines;
    A comparator that compares a data voltage corresponding to the data line driving circuit to be corrected among the plurality of data line driving circuits with a comparator reference voltage;
    A correction data calculation unit that calculates correction data for correcting variations in the data voltage based on a comparison result from the comparator;
    A plurality of correction circuits that correct the image data based on the correction data from the correction data calculation unit and output the corrected image data to a corresponding data line driving circuit among the plurality of data line driving circuits; ,
    Only including,
    In the correction data calculation mode, the correction data calculation unit sequentially changes the measurement data and outputs the measurement data to the correction target data line driving circuit, and the correction target data line driving circuit outputs a data voltage corresponding to the measurement data. The comparator compares the data voltage corresponding to the measurement data with a comparator reference voltage, the correction data calculation unit calculates the correction data based on the comparison result from the comparator,
    In the normal operation mode, the correction circuit corrects the image data based on the correction data, and outputs the corrected image data to the corresponding data line driving circuit among the plurality of data line driving circuits.
    The correction data calculator is
    In the correction data calculation mode, when the measurement data is sequentially changed within a predetermined range, the comparison result of the comparator is fixed at either the first level or the second level. An integrated circuit device characterized in that an overflow is determined, and overflow data is output as correction data for the correction target data line driving circuit .
  2. In claim 1 ,
    The correction data calculation unit
    An integrated circuit device, wherein the correction data calculation mode is executed in one horizontal scanning period in a non-display period of the vertical scanning period to calculate the correction data.
  3. In claim 1 or 2 ,
    The correction data calculation unit
    The first to kth (k is a natural number) measurement gradation data is sequentially output as the measurement data,
    The comparator is
    A comparator reference voltage, which is a voltage between a gray scale voltage corresponding to the first measurement gray scale data and a gray scale voltage corresponding to the k th measurement gray scale data, and a correction target data line driving circuit; An integrated circuit device characterized by comparing corresponding data voltages.
  4. In any one of Claims 1 thru | or 3 ,
    Including a control unit for setting gradation data corresponding to a predetermined data voltage;
    In the first horizontal scanning period among the plurality of horizontal scanning periods in the non-display period, the plurality of data line driving circuits output the predetermined data voltage corresponding to the grayscale data, whereby the plurality of data A voltage supply line is set to the predetermined data voltage;
    An integrated circuit device, wherein the correction data calculation unit obtains the correction data in a second horizontal scanning period following the first horizontal scanning period among a plurality of horizontal scanning periods in a non-display period.
  5. In any one of Claims 1 thru | or 4 ,
    The correction data calculator is
    In the correction data calculation mode, the correction data obtained from the comparison result of the comparator is multiplied by the correction coefficient to obtain correction data after coefficient multiplication,
    The plurality of correction circuits include:
    An integrated circuit device that corrects image data based on the correction data after coefficient multiplication in the normal operation mode.
  6. In any one of Claims 1 thru | or 5 ,
    The correction data calculator is
    An integrated circuit device that outputs gradation data between the maximum gradation data and the minimum gradation data of the measurement data as the overflow data.
  7. In any one of Claims 1 thru | or 6 .
    Each data line driving circuit of the plurality of data line driving circuits is
    Multiplex driving for writing data voltages to a plurality of pixels in one horizontal scanning period;
    The correction data calculator is
    In one horizontal scanning period in the non-display period of the vertical scanning period, a plurality of correction calculation data for the correction target data line driving circuit is obtained, and the correction data is obtained based on the plurality of correction calculation data. An integrated circuit device.
  8. In claim 7 ,
    The correction data calculator is
    An integrated circuit device, wherein the correction data is obtained by averaging the plurality of correction calculation data.
  9. In claim 7 or 8 ,
    The correction data calculator is
    In the correction data calculation mode, when the measurement data is sequentially changed within a predetermined range, the comparison result of the comparator is fixed at either the first level or the second level. An integrated circuit device characterized in that it is determined that an overflow has occurred, and the overflow data is used as correction calculation data for the data line drive circuit to be corrected.
  10. In claim 9 ,
    The correction data calculator is
    An integrated circuit device characterized by using gradation data between the maximum gradation data and the minimum gradation data of the measurement data as overflow data used as the correction calculation data .
  11. In claim 9 ,
    The correction data calculator is
    If it is determined that the overflow occurs when obtaining the s-th correction calculation data (1 ≦ s ≦ t, where s and t are integers of 2 or more) among the first to t-th correction calculation data, The first to s-1th correction calculation data among the first to tth correction calculation data is averaged to obtain overflow data, which is used as the sth correction calculation data. Integrated circuit device.
  12. In any one of Claims 1 thru | or 11 ,
    The correction data calculator is
    Correction data to be output to a correction circuit corresponding to the correction target data line driving circuit among the plurality of correction circuits using the current correction data obtained for the correction target data line driving circuit and the previous correction data. An integrated circuit device characterized by:
  13. In claim 12 ,
    The correction data calculator is
    When the current correction data is larger than the previous correction data, the correction data is obtained by adding a positive predetermined value to the previous correction data, and the current correction data is smaller than the previous correction data. In such a case, the correction data is obtained by adding a negative predetermined value to the previous correction data.
  14. In any one of Claims 1 thru | or 13 .
    The plurality of data line driving circuits are arranged along a first direction;
    When the direction opposite to the first direction is the second direction,
    The comparator is not arranged between the data line driving circuits of the plurality of data line driving circuits, but is arranged in the first direction or the second direction of the plurality of data line driving circuits. An integrated circuit device.
  15. An electronic apparatus comprising the integrated circuit device according to any one of claims 1 to 14.
JP2008226368A 2008-09-03 2008-09-03 Integrated circuit device and electronic apparatus Active JP4849107B2 (en)

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